Where do Yahoo! Web Analytics get its Demographic data?

Well first of all Yahoo! has some 550.000.000 unique visitors every month and those visitors are giving their data away by signing and out of various services such as Flickr, del.icio.us, Kelkoo (a shopping search engine which operates in 10 European countries), Yahoo! Answers, Yahoo! Messenger, Yahoo! Mail serving over 260 million users, Yahoo! GeoCities, and Yahoo! Finance, Yahoo! Games, Yahoo! Gallery, Yahoo! Buzz and more. This data is a sample of information collected across the Yahoo Network.

A list of some of the Yahoo! owned sites and services:

http://answers.yahoo.com/question/index?qid=20081007214624AAfLXEF and
http://en.wikipedia.org/wiki/List_of_Yahoo!-owned_sites_and_services+Yahoo+owned+web+sites

European Search Personality of the year 2014, Kristján Már Hauksson, is the Co-Founder and COO of SMFB Engine, based in Oslo, Norway.
This newfound digital activation/marketing agency works closely with the award winning creative agency, SMFB, in making sure that each idea has the digital presence to make it fly. Kristján is a publish author on the topic Internet Marketing and Search Engine Marketing.